The visibility of gratings: Spatial frequency channels or bar-detecting units?

Macleod, Iain; Rosenfeld, Azriel

doi:10.1016/0042-6989(74)90157-6

Cited by 48 publications

(9 citation statements)

References 30 publications

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“…Recent psychophysical work by Wilson & Giese (1977), Wilson & Bergen (1979) (see also Macleod & Rosenfeld 1974), has led to a precise quantitative model of the orientation-dependent spatial-frequency-tuned channels discovered by Campbell & Robson (1968). At each point in the visual field, there are four such channels spanning about three octaves, and their peak sensitivity wavelength increases linearly with retinal eccentricity.…”

Section: The Empirical Datamentioning

confidence: 99%

Theory of edge detection

Marr

Hildreth

1980

Proc. R. Soc. Lond. B.

4,847

774

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A theory of edge detection is presented. The analysis proceeds in two parts.(1) Intensity changes, which occur in a natural image over a wide range of scales, are detected separately at different scales. An appropriate filter for this purpose a t a given scale is found to be the second derivative of a Gaussian, and it is shown th a t, provided some simple conditions are satisfied, these prim ary filters need not be orientation-dependent. Thus, intensity changes a t a given scale are best detected by finding the zero values of V2G(x, y)* I(x, y) for image I, where G(x, y) is a two-dimen sional Gaussian distribution and V2 is the Laplacian. The intensity changes thus discovered in each of the channels are then represented by oriented primitives called zero-crossing segments, and evidence is given th a t this representation is complete. (2) Intensity changes in images arise from surface discontinuities or from reflectance or illumination bound aries, and these all have the property th a t they are spatially localized. Because of this, the zero-crossing segments from the different channels are not independent, and rules are deduced for combining them into a description of the image. This description is called the raw primal sketch. The theory explains several basic psychophysical findings, and the opera tion of forming oriented zero-crossing segments from the output of centre-surround V2G filters acting on the image forms the basis for a physiological model of simple cells (see .

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Section: The Empirical Datamentioning

confidence: 99%

Theory of edge detection

Marr

Hildreth

1980

Proc. R. Soc. Lond. B.

4,847

774

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“…It is well accepted that cells in the primary visual cortex works as multiorientation and multiscale filters, which respond to the luminance contrast of spatial patterns at specific retinal positions (De Valois & De Valois, 1980;Legge & Foley, 1980;Macleod & Rosenfeld, 1974;Stromeyer & Klein, 1974;Thomas, 1970;Wilson & Bergen, 1979). However, psychophysical studies have shown that the presence of co-aligned adjacent stimuli (flanker) lower the contrast detection threshold of flanked test stimuli (Cass & Alais, 2006;Chen & Tyler, 2001, 2008Polat & Sagi, 1993, 1994Williams & Hess, 1998;Woods, Nugent, & Peli, 2002;Yu, Klein, & Levi, 2002).…”

Section: Introductionmentioning

confidence: 99%

The effects of flankers on contrast detection and discrimination in binocular, monocular, and dichoptic presentations

Maehara

Huang

Hess

2010

JOV

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We investigated how two co-aligned adjacent stimuli (flankers) influence threshold versus pedestal contrast (TvC) functions in binocular, monocular, and dichoptic presentations. Targets were presented to the two eyes or to only one eye. Pedestals and flankers were presented to the same eye to which the target was presented (binocular or monocular presentations) or to the other eye (dichoptic presentation). In the binocular presentation of targets and pedestals, the binocular flankers lowered thresholds at low pedestal contrasts. The monocular flankers had a similar effect to the binocular flanker, although the threshold reduction was smaller. In the dichoptic presentation of a target and a pedestal, flankers lowered thresholds when flankers were presented to the eye where targets were presented. In contrast, dichoptic flankers elevated thresholds at intermediate pedestal contrasts when a pedestal was also dichoptically presented. We fitted binocular contrast gain control models to the data. It follows from the fitting results that flankers modulate outputs from spatial filters in the monocular processing stage of contrast gain control.

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“…There are those who have supported this view (e.g., 2, 3, B), and there are those who have questioned it (e.g., 6,7,9). Therefore, an analytical strategy, which the visual system might take in parsing the visual scene, would be to analyze the complex wave into its sine wave components by ~e r f o r m i n~ a Fourier analysis.…”

mentioning

confidence: 99%

The Problem of the Missing Wavelet

Brigner

1999

Percept Mot Skills

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A block face was generated by dividing a drawn face into a matrix of rectangular cells and then making the brightness of each cell equal to the average of the brightnesses within the facial area circumscribed by a cell. A wavelet analysis was performed on the numbers representing the brightnesses of the cells in each row of the matrix, and from each row, the wavelet was deleted which corresponded to the fundamental or the lowest frequency sine wave of a complex wave. The appearance of the block face was not substantially altered by the deletion of the wavelet corresponding to the fundamental.

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The visibility of gratings: Spatial frequency channels or bar-detecting units?

Cited by 48 publications

References 30 publications

Theory of edge detection

Theory of edge detection

The effects of flankers on contrast detection and discrimination in binocular, monocular, and dichoptic presentations

The Problem of the Missing Wavelet

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